JP2017151142A

JP2017151142A - Display device

Info

Publication number: JP2017151142A
Application number: JP2016030895A
Authority: JP
Inventors: 清史澤田; Kiyoshi Sawada; 勲米岡; Isao Yoneoka; 浅村　吉範; Yoshinori Asamura; 吉範浅村
Original assignee: Mitsubishi Electric Corp
Current assignee: Mitsubishi Electric Corp
Priority date: 2016-02-22
Filing date: 2016-02-22
Publication date: 2017-08-31

Abstract

PROBLEM TO BE SOLVED: To provide a display device that can reduce the power consumption of each of a plurality of semiconductor light-emitting devices which is connected to an anode common and whose forward voltage drops are different, while supplying common forward voltage to the semiconductor light-emitting devices.SOLUTION: A display device includes a display portion including a semiconductor light-emitting device array, and driving means that drives the display portion. The semiconductor light-emitting device array includes a semiconductor light-emitting device whose forward voltage drop is different from that of another semiconductor light-emitting device included in the same semiconductor light-emitting device array. The driving means includes a power source that applies the common forward voltage to the anodes of the semiconductor light-emitting devices included in the semiconductor light-emitting device array, and boosting means that is connected to a cathode side of the semiconductor light-emitting device that is different from the semiconductor light-emitting device with the maximum forward voltage drop among the semiconductor light-emitting devices, and boosts the potential on the cathode side.SELECTED DRAWING: Figure 2

Description

本発明は、複数の半導体発光デバイスを備える表示装置に関するものである。 The present invention relates to a display device including a plurality of semiconductor light emitting devices.

ＬＥＤ（ＬｉｇｈｔＥｍｉｔｔｉｎｇＤｉｏｄｅ：発光ダイオード）を画素として備える表示装置は、屋外や屋内問わず広告等の表示に多く使用されている。近年では、ＬＥＤの低コスト化に伴い表示装置の多画素化が進んでいる。多画素化された表示装置の画素ピッチは表示面サイズが従来の装置と同じであったとしても狭くなる。例えば、従来の大型表示装置の画素ピッチは３ｍｍ以上のものが主流であったが、近年では多画素化が進んだ結果、画素ピッチ１．５ｍｍや１．９ｍｍの製品が市場に投入されている。 A display device including an LED (Light Emitting Diode) as a pixel is often used for displaying advertisements, whether outdoors or indoors. In recent years, the number of pixels in display devices has been increasing with the reduction in cost of LEDs. The pixel pitch of a multi-pixel display device is narrow even if the display surface size is the same as that of a conventional device. For example, a conventional large display device has a pixel pitch of 3 mm or more, but as a result of the recent increase in the number of pixels, products with a pixel pitch of 1.5 mm or 1.9 mm have been put on the market. .

画素の狭ピッチ化に伴い１画素を構成するＬＥＤのパッケージも小型化されており、なかには、１．０ｍｍ×１．０ｍｍ以下の非常に小さなパッケージで構成されるＬＥＤも存在する。そのような小型パッケージのＬＥＤが有する実装用の電極面積は、従来のパッケージの電極面積よりも小さく、また多画素化によって端子数も多くなることから、例えば半田付け工程等の製造工程における歩留まりが低下する。また、配線パターンも複雑化し、実装基板の層数増加によるコストアップが生じる。 Along with the narrowing of the pitch of pixels, the package of an LED that constitutes one pixel is also reduced in size, and there is also an LED that is constituted by a very small package of 1.0 mm × 1.0 mm or less. The electrode area for mounting of such a small package LED is smaller than the electrode area of the conventional package, and the number of terminals increases due to the increase in the number of pixels. For example, the yield in the manufacturing process such as the soldering process is increased. descend. Also, the wiring pattern is complicated, and the cost increases due to an increase in the number of layers of the mounting substrate.

そこで、パッケージの端子数を必要最低限に抑えるため、画素を構成する赤・緑・青の各色ＬＥＤのアノードもしくはカソードを共通に接続した駆動回路を有するパッケージが使用されている。カソードコモンに接続した駆動回路においては、各ＬＥＤが有する順方向電圧降下に基づき、各ＬＥＤには各々異なる印加電圧が供給される。すなわち、各ＬＥＤに適正な電圧を個別に印加することができるため消費電力を抑制し、素子の寿命低下も防ぐことができる。しかしながら、カソードコモン接続に対応したドライバの製造メーカは限られており、量産効果が得られず結果的に表示装置のコストアップにつながる。特許文献１には、ドライバのコスト低減を目的に、複数色のＬＥＤをカソードコモンに接続し、それらアノードはスイッチング素子に接続した駆動回路が開示されている。 Therefore, in order to minimize the number of terminals of the package, a package having a drive circuit in which anodes or cathodes of red, green, and blue LEDs constituting a pixel are connected in common is used. In the drive circuit connected to the cathode common, each LED is supplied with a different applied voltage based on the forward voltage drop of each LED. That is, since an appropriate voltage can be individually applied to each LED, power consumption can be suppressed and the life of the element can be prevented from being reduced. However, manufacturers of drivers that support cathode common connection are limited, and mass production effects cannot be obtained, resulting in an increase in the cost of the display device. Patent Document 1 discloses a drive circuit in which LEDs of a plurality of colors are connected to a cathode common and the anodes are connected to a switching element for the purpose of reducing the cost of the driver.

特許第３５６４３５９号公報（段落００３８〜００４７および図５）Japanese Patent No. 3564359 (paragraphs 0038 to 0047 and FIG. 5)

一方で、各ＬＥＤをアノードコモンに接続した駆動回路においては、各ＬＥＤに共通の印加電圧が供給される。すなわち赤・緑・青の各ＬＥＤが有する順方向電圧降下のうち、最大の順方向電圧降下以上の電圧を供給し、全てのＬＥＤが発光可能な構成としている。このような構成では、順方向電圧降下が小さなＬＥＤにとって、その供給電圧と順方向電圧降下との差が無駄な消費電力となる。その消費電力は熱エネルギーへと変換されるため、結果的に温度上昇に伴うＬＥＤの寿命低下を引き起こす。 On the other hand, in a drive circuit in which each LED is connected to the anode common, a common applied voltage is supplied to each LED. That is, among the forward voltage drops of the red, green, and blue LEDs, a voltage that is equal to or greater than the maximum forward voltage drop is supplied, and all LEDs can emit light. In such a configuration, for an LED having a small forward voltage drop, the difference between the supply voltage and the forward voltage drop is a wasteful power consumption. Since the power consumption is converted into thermal energy, the lifetime of the LED is reduced as the temperature rises.

本発明は、以上のような課題を解決するためになされたものであり、アノードコモンに接続した順方向電圧降下が異なる複数の半導体発光デバイスに対し共通の順方向電圧を供給しながらも、各半導体発光デバイスの電力消費を低減することが可能な表示装置を提供することを目的とする。 The present invention has been made to solve the above-described problems, and while supplying a common forward voltage to a plurality of semiconductor light emitting devices having different forward voltage drops connected to the anode common, An object is to provide a display device capable of reducing power consumption of a semiconductor light emitting device.

半導体発光デバイスアレイを含む表示部と、表示部を電気的に駆動する駆動手段とを備える表示装置であって、半導体発光デバイスアレイは、同じ半導体発光デバイスアレイに含まれる他の半導体発光デバイスが有する順方向電圧降下とは異なる順方向電圧降下を有する少なくとも１つの半導体発光デバイスを含み、駆動手段は、各半導体発光デバイスアレイに含まれる半導体発光デバイスの各アノードに共通の順方向電圧を印加する電源と、各半導体発光デバイスアレイに含まれる半導体発光デバイスのうち、最大の順方向電圧降下を有する半導体発光デバイスとは異なる少なくとも１つの半導体発光デバイスのカソード側に接続し、当該カソード側の電位を昇圧させる少なくとも１つの昇圧手段とを備える。 A display device including a display unit including a semiconductor light emitting device array and a driving unit that electrically drives the display unit, the semiconductor light emitting device array having other semiconductor light emitting devices included in the same semiconductor light emitting device array A power supply including at least one semiconductor light emitting device having a forward voltage drop different from the forward voltage drop, wherein the driving means applies a common forward voltage to each anode of the semiconductor light emitting devices included in each semiconductor light emitting device array. Are connected to the cathode side of at least one semiconductor light emitting device different from the semiconductor light emitting device having the maximum forward voltage drop among the semiconductor light emitting devices included in each semiconductor light emitting device array, and the potential on the cathode side is boosted. And at least one boosting means.

本発明に係る表示装置によれば、アノードコモンに接続した順方向電圧降下が異なる複数の半導体発光デバイスに対し共通の順方向電圧を供給しながらも、各半導体発光デバイスの電力消費を低減することができる表示装置の提供が可能である。 According to the display device of the present invention, it is possible to reduce power consumption of each semiconductor light emitting device while supplying a common forward voltage to a plurality of semiconductor light emitting devices connected to the anode common and having different forward voltage drops. It is possible to provide a display device that can be used.

本発明の実施の形態における表示装置のブロック図である。It is a block diagram of a display device in an embodiment of the invention. 本発明の実施の形態における駆動手段のブロック図である。It is a block diagram of the drive means in the embodiment of the present invention. 表示装置が備える定電流回路の印加電圧と出力電流の関係を示した図である。It is the figure which showed the relationship between the applied voltage and output current of a constant current circuit with which a display apparatus is equipped. 本発明の実施の形態における各ＬＥＤの点灯制御のタイミングを示す図である。It is a figure which shows the timing of lighting control of each LED in embodiment of this invention.

本発明に係る表示装置の実施の形態について以下に図を用いて説明する。 Embodiments of a display device according to the present invention will be described below with reference to the drawings.

（表示装置）
図１は、本実施の形態の表示装置の内部を模式的に表したブロック図である。本実施の形態の表示装置１は、映像や画像を表示する表示部１０と、その表示部１０を電気的に駆動する駆動手段として駆動部２０とを備える。また、表示装置１は、外部からの映像信号を入力する入力端子２と、その入力した映像信号から表示領域を選択する処理あるいはガンマ補正などの画像処理を行う映像信号処理部３と、その映像信号処理部３の出力信号の輝度を補正する輝度補正部４とを備える。 (Display device)
FIG. 1 is a block diagram schematically showing the inside of the display device of the present embodiment. The display device 1 according to the present embodiment includes a display unit 10 that displays video and images, and a drive unit 20 as a drive unit that electrically drives the display unit 10. The display device 1 also includes an input terminal 2 for inputting an external video signal, a video signal processing unit 3 for performing processing such as selecting a display area from the input video signal or performing image processing such as gamma correction, and the video. And a luminance correction unit 4 for correcting the luminance of the output signal of the signal processing unit 3.

表示部１０は、その面内にマトリックス状に配列された複数の半導体発光デバイスアレイ２００を備える。さらに、各半導体発光デバイスアレイ２００は複数の半導体発光デバイス１００を含む。本実施の形態においては、表示部１がカラー表示機能を有するため、半導体発光デバイスアレイ２００は、赤色の波長域で発光する半導体発光デバイス１００Ｒと、緑色の波長域で発光する半導体発光デバイス１００Ｇと、青色の波長域で発光する半導体発光デバイス１００Ｂとを含む。また、それら同じ半導体発光デバイスアレイ２００に含まれる複数の半導体発光デバイス１００のうち少なくとも１つの半導体発光デバイス１００は、その他の半導体発光デバイス１００が有する順方向電圧降下とは異なる順方向電圧降下を有する。本実施の形態においては、赤色で発光する半導体発光デバイス１００Ｒの順方向電圧降下と青色で発光する半導体発光デバイス１００Ｂの順方向電圧降下とは異なる。なお、それら半導体発光デバイス１００とはダイオードを用いた発光デバイスのことであり、例えば、ＬＥＤや半導体レーザーである。本実施の形態において、表示装置１はカラー表示機能を有するＬＥＤ表示装置であり、表示部１０はマトリックス状に配列された複数のＬＥＤアレイ２００を備え、そのＬＥＤアレイ２００は赤色ＬＥＤ１００Ｒと緑色ＬＥＤ１００Ｇと青色ＬＥＤ１００Ｂとを備える。 The display unit 10 includes a plurality of semiconductor light emitting device arrays 200 arranged in a matrix in the plane. Further, each semiconductor light emitting device array 200 includes a plurality of semiconductor light emitting devices 100. In the present embodiment, since the display unit 1 has a color display function, the semiconductor light emitting device array 200 includes a semiconductor light emitting device 100R that emits light in the red wavelength region, and a semiconductor light emitting device 100G that emits light in the green wavelength region. And a semiconductor light emitting device 100B that emits light in a blue wavelength region. Further, at least one semiconductor light emitting device 100 among the plurality of semiconductor light emitting devices 100 included in the same semiconductor light emitting device array 200 has a forward voltage drop different from the forward voltage drop of the other semiconductor light emitting devices 100. . In the present embodiment, the forward voltage drop of the semiconductor light emitting device 100R that emits red light is different from the forward voltage drop of the semiconductor light emitting device 100B that emits blue light. The semiconductor light emitting device 100 is a light emitting device using a diode, such as an LED or a semiconductor laser. In the present embodiment, the display device 1 is an LED display device having a color display function, and the display unit 10 includes a plurality of LED arrays 200 arranged in a matrix, and the LED array 200 includes a red LED 100R and a green LED 100G. And a blue LED 100B.

表１は、表示部１０に含まれる各ＬＥＤが有する活性層の材料と、各ＬＥＤの順方向電圧降下Ｖ_ｆの値とを示す。一般的に順方向電圧降下Ｖ_ｆは、半導体発光デバイスの活性層材料に依存する。緑色ＬＥＤ１００Ｇの順方向電圧降下Ｖ_ｆと青色ＬＥＤ１００Ｂの順方向電圧降下Ｖ_ｆとは同じ値であるが、赤色ＬＥＤ１００Ｒの順方向電圧降下Ｖ_ｆはそれらと比較して１．０Ｖ低い。なお、表１に示した順方向電圧降下Ｖ_ｆの値は一例でありこれらに限るものではない。 Table 1 shows the material of the active layer of each LED included in the display unit 10 and the value of the forward voltage drop V _f of each LED. Generally, the forward voltage drop V _f depends on the active layer material of the semiconductor light emitting device. Although the forward voltage drop _{V f} and blue LED100B forward voltage drop _{V f} green LED100G the same value, the forward voltage drop _{V f} in the red LED100R 1.0 V lower than that of them. In addition, the value of the forward voltage drop _Vf shown in Table 1 is an example, and is not limited thereto.

（半導体発光デバイスアレイ内の接続構成）
図２は、表示部１０に電気的に接続された駆動部２０の内部を表すブロック図である。表示部１０は、第１の方向すなわち横方向に２つのＬＥＤアレイと、第２の方向すなわち縦方向に２つのＬＥＤアレイとをマトリックス状に配列して備える。実際の表示装置に備わるＬＥＤアレイの数は、図２の表示装置１のその数よりも多いが、ここでは本発明の説明を簡単にするために、４つのＬＥＤアレイを含む表示装置１を用いて本発明を説明する。 (Connection configuration in semiconductor light emitting device array)
FIG. 2 is a block diagram showing the inside of the drive unit 20 electrically connected to the display unit 10. The display unit 10 includes two LED arrays in a first direction, that is, a horizontal direction, and two LED arrays in a second direction, that is, a vertical direction, arranged in a matrix. Although the actual number of LED arrays included in the display device is larger than that of the display device 1 of FIG. 2, here, in order to simplify the description of the present invention, the display device 1 including four LED arrays is used. The present invention will be described.

図２において、ＬＥＤアレイの配列に関して、第１の方向（横方向）を行、第２の方向（縦方向）を列とした場合、図２に記載した駆動部２０を備える表示装置１は、１行１列目にＬＥＤアレイ２１１と１行２列目にＬＥＤアレイ２１２とを備える。また、表示装置１は、２行１列目にＬＥＤアレイ２２１と、２行２列目にＬＥＤアレイ２２２とを備える。各ＬＥＤアレイは、赤色ＬＥＤと緑色ＬＥＤと青色ＬＥＤとを含む。また、ＬＥＤアレイは、各ＬＥＤが有する各アノードを共通に接続したアノードコモン端子を備える。以下これら接続を具体的に説明する。 In FIG. 2, regarding the arrangement of the LED array, when the first direction (horizontal direction) is a row and the second direction (vertical direction) is a column, the display device 1 including the drive unit 20 illustrated in FIG. The LED array 211 is provided in the first row and the first column, and the LED array 212 is provided in the first row and the second column. Further, the display device 1 includes an LED array 221 in the second row and the first column and an LED array 222 in the second row and the second column. Each LED array includes a red LED, a green LED, and a blue LED. The LED array also includes an anode common terminal in which the anodes of the LEDs are connected in common. These connections will be specifically described below.

１行１列目のＬＥＤアレイ２１１は赤色ＬＥＤ１１１Ｒと緑色ＬＥＤ１１１Ｇと青色ＬＥＤ１１１Ｂとを含む。また、ＬＥＤアレイ２１１はアノードコモン端子３１１を備え、赤色ＬＥＤ１１１Ｒのアノードと緑色ＬＥＤ１１１Ｇのアノードと青色ＬＥＤ１１１Ｂアノードとは、アノードコモン端子３１１に共通に接続されている。すなわち各アノードはアノードコモンに接続されている。他のＬＥＤアレイの構成もＬＥＤアレイ２１１と同様である。ＬＥＤアレイ２１２は、赤色ＬＥＤ１１２Ｒと緑色ＬＥＤ１１２Ｇと青色ＬＥＤ１１２Ｂとを含み、それら各アノードはＬＥＤアレイ２１２が備えるアノードコモン端子３１２に共通に接続される。ＬＥＤアレイ２２１は、赤色ＬＥＤ１２１Ｒと緑色ＬＥＤ１２１Ｇと青色ＬＥＤ１２１Ｂとを含み、それら各アノードはＬＥＤアレイ２２１が備えるアノードコモン端子３２１に共通に接続される。ＬＥＤアレイ２２２は、赤色ＬＥＤ１２２Ｒと緑色ＬＥＤ１２２Ｇと青色ＬＥＤ１２２Ｂとを含み、それら各アノードはＬＥＤアレイ２２２が備えるアノードコモン端子３２２に共通に接続される。 The LED array 211 in the first row and the first column includes a red LED 111R, a green LED 111G, and a blue LED 111B. The LED array 211 includes an anode common terminal 311, and the anode of the red LED 111 </ b> R, the anode of the green LED 111 </ b> G, and the blue LED 111 </ b> B anode are commonly connected to the anode common terminal 311. That is, each anode is connected to the anode common. Other LED arrays have the same configuration as the LED array 211. The LED array 212 includes a red LED 112R, a green LED 112G, and a blue LED 112B, and each anode thereof is commonly connected to an anode common terminal 312 provided in the LED array 212. The LED array 221 includes a red LED 121R, a green LED 121G, and a blue LED 121B, and each anode thereof is commonly connected to an anode common terminal 321 included in the LED array 221. The LED array 222 includes a red LED 122R, a green LED 122G, and a blue LED 122B, and each anode thereof is commonly connected to an anode common terminal 322 included in the LED array 222.

（半導体発光デバイスアレイのアノード側の接続構成）
駆動部２０は各ＬＥＤの各アノードに共通の順方向電圧を印加する電源として電源供給回路３０を備える。本実施の形態においては、電源供給回路３０の出力は各ＬＥＤアレイの各アノードコモン端子と接続している。すなわち表示装置１はアノードコモン接続の構成を備える。 (Connection configuration on the anode side of the semiconductor light emitting device array)
The drive unit 20 includes a power supply circuit 30 as a power source that applies a common forward voltage to each anode of each LED. In the present embodiment, the output of the power supply circuit 30 is connected to each anode common terminal of each LED array. That is, the display device 1 has an anode common connection configuration.

その電源供給回路３０と各ＬＥＤアレイとの接続を以下に具体的に説明する。電源供給回路３０の出力は、表示装置１が含むＬＥＤアレイの行数と同じ数のラインに電気的に並列分岐する。図２の表示装置１の場合、その行数は２行であるので、電源供給回路３０の出力はラインＬ１とラインＬ２の２本に分岐する。ラインＬ１は、さらにＬＥＤアレイの列数と同じ数のラインに電気的に並列分岐する。すなわち図２の表示装置１の場合、その列数は２列であるので、ラインＬ１はラインＬ１１とＬ１２との２本に分岐する。ラインＬ１１はＬＥＤアレイ２１１のアノードコモン端子３１１に接続する。ラインＬ１２はＬＥＤアレイ２１２のアノードコモン端子３１２に接続する。同様に、ラインＬ２はラインＬ２１とＬ２２との２本に分岐する。ラインＬ２１はＬＥＤアレイ２２１のアノードコモン端子３２１に接続する。ラインＬ２２はＬＥＤアレイ２２２のアノードコモン端子３２２に接続する。 The connection between the power supply circuit 30 and each LED array will be specifically described below. The output of the power supply circuit 30 is electrically branched in parallel into as many lines as the number of rows of the LED array included in the display device 1. In the case of the display device 1 of FIG. 2, since the number of rows is two, the output of the power supply circuit 30 branches into two lines L1 and L2. The line L1 is further electrically branched in parallel into the same number of lines as the number of columns of the LED array. That is, in the case of the display device 1 of FIG. 2, since the number of columns is two, the line L1 branches into two lines L11 and L12. The line L11 is connected to the anode common terminal 311 of the LED array 211. The line L12 is connected to the anode common terminal 312 of the LED array 212. Similarly, the line L2 branches into two lines L21 and L22. The line L21 is connected to the anode common terminal 321 of the LED array 221. The line L22 is connected to the anode common terminal 322 of the LED array 222.

駆動部２０は、第１の方向すなわち行方向に配列された各ＬＥＤアレイに流れる電流または印加する電圧の入出力を時分割制御する第１の点灯制御手段を備える。本実施の形態において、その第１の点灯制御手段はスイッチ４１とスイッチ４２である。駆動部２０は、スイッチ４１をラインＬ１上に備え、そのラインＬ１が複数本に分岐する結線部よりも、すなわちラインＬ１がラインＬ１１に分岐する位置よりも電源供給回路３０側に設けられる。これにより、スイッチ４１は、１ライン目であるラインＬ１に接続するＬＥＤアレイ２１１とＬＥＤアレイ２１２への電圧供給を一括で入切する機能を有する。また、駆動部２０は、ラインＬ２上にもう１つの第１の点灯制御手段としてスイッチ４２をさらに備える。そのスイッチ４２はラインＬ２が複数本に分岐する別の結線部よりも、すなわち、本実施の形態においてはラインＬ２がラインＬ２１に分岐する位置よりも電源供給回路３０側に設けられる。スイッチ４２は、２ライン目であるラインＬ２に接続するＬＥＤアレイ２２１とＬＥＤアレイ２２２への電圧供給を一括で入切する機能を有する。 The drive unit 20 includes first lighting control means for performing time-sharing control on input / output of currents or voltages to be applied to the LED arrays arranged in the first direction, that is, the row direction. In the present embodiment, the first lighting control means is a switch 41 and a switch 42. The drive unit 20 includes the switch 41 on the line L1, and is provided closer to the power supply circuit 30 than the connection unit where the line L1 branches into a plurality of lines, that is, the position where the line L1 branches into the line L11. Thereby, the switch 41 has a function of turning on and off the voltage supply to the LED array 211 and the LED array 212 connected to the line L1 which is the first line in a lump. The drive unit 20 further includes a switch 42 as another first lighting control unit on the line L2. The switch 42 is provided closer to the power supply circuit 30 than another connection portion where the line L2 branches into a plurality of lines, that is, the position where the line L2 branches into the line L21 in the present embodiment. The switch 42 has a function of collectively turning on / off the voltage supply to the LED array 221 and the LED array 222 connected to the second line L2.

（半導体発光デバイスアレイのカソード側の接続構成）
また、駆動部２０は、各ＬＥＤのカソード側に接続する定電流回路６０をさらに備える。また駆動部２０は、第２の方向すなわち列方向に配列された各ＬＥＤアレイに含まれる各ＬＥＤの各カソードに接続する配線上に第２の点灯制御手段をさらに備える。第２の点灯制御手段は、列方向に配列された各ＬＥＤに流れる電流または印加する電圧の入出力を時分割制御する。本実施の形態において、駆動部２０は第２の点灯制御手段としてＯＮ／ＯＦＦ回路７０を備える。定電流回路６０とＯＮ／ＯＦＦ回路７０とは、列ごとにかつＬＥＤの種類ごとに設けられる。以下、これらの接続関係を１列目に配置されるＬＥＤアレイ２１１およびＬＥＤアレイ２２１の各カソード側を例にして具体的に説明する。 (Connection configuration on the cathode side of the semiconductor light emitting device array)
The drive unit 20 further includes a constant current circuit 60 connected to the cathode side of each LED. The drive unit 20 further includes second lighting control means on the wiring connected to each cathode of each LED included in each LED array arranged in the second direction, that is, the column direction. The second lighting control means time-division-controls the input / output of the current flowing through the LEDs arranged in the column direction or the voltage to be applied. In the present embodiment, the drive unit 20 includes an ON / OFF circuit 70 as second lighting control means. The constant current circuit 60 and the ON / OFF circuit 70 are provided for each column and each LED type. Hereinafter, these connection relationships will be described in detail by taking the cathode side of the LED array 211 and the LED array 221 arranged in the first column as an example.

１行１列目の赤色ＬＥＤ１１１Ｒのカソードと、２行１列目の赤色ＬＥＤ１２１Ｒのカソードとは、共通に定電流回路６１Ｒの一端と接続する。その定電流回路６１Ｒの他端はＯＮ／ＯＦＦ回路７１Ｒの一端と接続する。同様に、１行１列目の緑色ＬＥＤ１１１Ｇのカソードと２行１列目の緑色ＬＥＤ１２１Ｇのカソードとは、共通に定電流回路６１Ｇの一端と接続する。その定電流回路６１Ｇの他端はＯＮ／ＯＦＦ回路７１Ｇの一端と接続する。同様に、１行１列目の青色ＬＥＤ１１１Ｂのカソードと２行１列目の青色ＬＥＤ１２１Ｂのカソードとは、共通に定電流回路６１Ｂの一端と接続する。その定電流回路６１Ｂの他端はＯＮ／ＯＦＦ回路７１Ｂの一端と接続する。 The cathode of the red LED 111R in the first row and first column and the cathode of the red LED 121R in the second row and first column are commonly connected to one end of the constant current circuit 61R. The other end of the constant current circuit 61R is connected to one end of the ON / OFF circuit 71R. Similarly, the cathode of the green LED 111G in the first row and first column and the cathode of the green LED 121G in the second row and first column are commonly connected to one end of the constant current circuit 61G. The other end of the constant current circuit 61G is connected to one end of the ON / OFF circuit 71G. Similarly, the cathode of the blue LED 111B in the first row and first column and the cathode of the blue LED 121B in the second row and first column are commonly connected to one end of the constant current circuit 61B. The other end of the constant current circuit 61B is connected to one end of the ON / OFF circuit 71B.

駆動部２０は、赤色ＬＥＤのカソード側の電位を昇圧させる昇圧手段として電源回路５０をさらに備える。本実施の形態において、上述したＯＮ／ＯＦＦ回路７１Ｒの他端は電源回路５０に接続する。つまり赤色ＬＥＤ１１１Ｒのカソードと赤色ＬＥＤ１２１Ｒのカソードとは、定電流回路６１ＲとＯＮ／ＯＦＦ回路７１Ｒとを通じて電源回路５０の一端と接続する。なお電源回路５０の他端はＧＮＤ電位に接続する。 The drive unit 20 further includes a power supply circuit 50 as boosting means for boosting the potential on the cathode side of the red LED. In the present embodiment, the other end of the above-described ON / OFF circuit 71R is connected to the power supply circuit 50. That is, the cathode of the red LED 111R and the cathode of the red LED 121R are connected to one end of the power supply circuit 50 through the constant current circuit 61R and the ON / OFF circuit 71R. The other end of the power supply circuit 50 is connected to the GND potential.

一方で、緑色ＬＥＤ１１１Ｇのカソード側と緑色ＬＥＤ１２１Ｇのカソード側とは、定電流回路６１ＧとＯＮ／ＯＦＦ回路７１Ｇとを通じてＧＮＤと接続する。同様に、青色ＬＥＤ１１１Ｂのカソード側と青色ＬＥＤ１２１Ｂのカソード側とは、定電流回路６１ＢとＯＮ／ＯＦＦ回路７１Ｂとを通じてＧＮＤと接続する。 On the other hand, the cathode side of the green LED 111G and the cathode side of the green LED 121G are connected to GND through the constant current circuit 61G and the ON / OFF circuit 71G. Similarly, the cathode side of the blue LED 111B and the cathode side of the blue LED 121B are connected to GND through the constant current circuit 61B and the ON / OFF circuit 71B.

以上１列目に配置されるＬＥＤアレイ２１１およびＬＥＤアレイ２２１の各カソード側の接続構成を説明したが、２列目に配置されるＬＥＤアレイ２１２およびＬＥＤアレイ２２２の各カソード側の接続構成も図２に示す通り同様である。すなわち、赤色ＬＥＤ１１２Ｒのカソードと赤色ＬＥＤ１２２Ｒのカソードとは、定電流回路６２ＲとＯＮ／ＯＦＦ回路７２Ｒを通じて電源回路５０の一端と接続する。緑色ＬＥＤ１１２Ｇのカソード側と緑色ＬＥＤ１２２Ｇのカソード側とは、定電流回路６２ＧとＯＮ／ＯＦＦ回路７２Ｇとを通じてＧＮＤと接続する。同様に、青色ＬＥＤ１１２Ｂのカソード側と青色ＬＥＤ１２２Ｂのカソード側とは、定電流回路６２ＢとＯＮ／ＯＦＦ回路７２Ｂとを通じてＧＮＤと接続する。 The connection configuration on the cathode side of the LED array 211 and LED array 221 arranged in the first column has been described above, but the connection configuration on the cathode side of the LED array 212 and LED array 222 arranged in the second column is also illustrated. This is the same as shown in FIG. That is, the cathode of the red LED 112R and the cathode of the red LED 122R are connected to one end of the power supply circuit 50 through the constant current circuit 62R and the ON / OFF circuit 72R. The cathode side of the green LED 112G and the cathode side of the green LED 122G are connected to GND through a constant current circuit 62G and an ON / OFF circuit 72G. Similarly, the cathode side of the blue LED 112B and the cathode side of the blue LED 122B are connected to GND through the constant current circuit 62B and the ON / OFF circuit 72B.

以上のように、電源回路５０は、各ＬＥＤアレイに含まれる各ＬＥＤのうち、最大の順方向電圧降下を有する各青色ＬＥＤと各緑色ＬＥＤとは異なるＬＥＤである各赤色ＬＥＤのカソード側に接続する。 As described above, the power supply circuit 50 is connected to the cathode side of each red LED that is different from each blue LED and each green LED having the maximum forward voltage drop among the LEDs included in each LED array. To do.

なお、電源回路５０は電源供給回路３０とも接続され、電源供給回路３０から駆動電源の供給を受ける。 The power supply circuit 50 is also connected to the power supply circuit 30 and receives supply of drive power from the power supply circuit 30.

駆動部２０は制御回路８０をさらに備える。制御回路８０はスイッチ４１とスイッチ４２と接続して制御信号を入出力し、それらスイッチのＯＮとＯＦＦを時分割制御する。また、制御回路８０は、各ＯＮ／ＯＦＦ回路７０とも接続し、ＯＮとＯＦＦの期間を時分割制御すなわちＰＷＭ（ＰｕｌｓｅＷｉｄｔｈＭｏｄｕｌａｔｉｏｎ）制御する。 The drive unit 20 further includes a control circuit 80. The control circuit 80 is connected to the switch 41 and the switch 42 to input / output control signals, and controls the ON and OFF of these switches in a time-sharing manner. The control circuit 80 is also connected to each ON / OFF circuit 70, and performs time-division control, that is, PWM (Pulse Width Modulation) control, during the ON and OFF periods.

（昇圧手段の動作と効果）
次に、昇圧手段である電源回路５０の動作と効果について述べる。各ＬＥＤは各アノードコモン端子を介して電源供給回路３０に共通に並列接続されているため、各ＬＥＤにはそれぞれ共通の順方向の印加電圧Ｖ_ｏが電源供給回路３０より供給される。 (Operation and effect of boosting means)
Next, the operation and effect of the power supply circuit 50 which is a boosting means will be described. Each LED because it is parallel connected in common to the power supply circuit 30 via the respective anode common terminal, the applied voltage V _o of each of the respective LED common forward direction is supplied from the power supply circuit 30.

その印加電圧Ｖ_ｏについて説明する。表１に示すように、赤色ＬＥＤは１０ｍＡの電流を流すために２．４Ｖの順方向電圧が必要であり、同様の条件で、緑色ＬＥＤと青色ＬＥＤとは３．４Ｖの順方向電圧が必要である。よって、アノードコモンに接続された赤・緑・青の３色の各ＬＥＤをすべて点灯させるためには、少なくとも３．４Ｖ以上の印加電圧Ｖ_ｏを電源供給回路３０が供給する必要がある。 It describes the applied voltage _{V o.} As shown in Table 1, the red LED needs a forward voltage of 2.4 V to pass a current of 10 mA, and under the same conditions, the green LED and the blue LED need a forward voltage of 3.4 V. It is. Accordingly, each LED of the three colors of the connected red, green, and blue anode common to make all lit, the power supply circuit 30 at least 3.4V or more of the applied voltage V _o needs to supply.

また印加電圧Ｖ_ｏに関して、それら各ＬＥＤの順方向電圧降下Ｖ_ｆの他に、定電流回路６０自体の電圧降下も考慮する必要がある。図３は、その定電流回路６０の印加電圧と出力電流の特性を示した図である。定電流回路６０に規定電流（出力電流）１０ｍＡの電流を流すためには、少なくとも０．５Ｖ以上の電圧を定電流回路６０に印加する必要がある。この電圧はニー電圧と呼ばれ、定電流回路６０を構成するトランジスタ特性に依存する。 Regarding the applied voltage V _o , it is necessary to consider the voltage drop of the constant current circuit 60 itself in addition to the forward voltage drop V _f of each LED. FIG. 3 is a diagram showing the characteristics of the applied voltage and output current of the constant current circuit 60. In order to pass a current of 10 mA specified current (output current) through the constant current circuit 60, it is necessary to apply a voltage of at least 0.5 V or more to the constant current circuit 60. This voltage is called a knee voltage and depends on the characteristics of the transistors constituting the constant current circuit 60.

したがって、本実施の形態において各ＬＥＤを点灯させるには、青色ＬＥＤおよび緑色ＬＥＤの順方向電圧降下Ｖ_ｆ＝３．４Ｖに、ニー電圧０．５Ｖを加えた３．９Ｖ以上の印加電圧が必要である。なお、実際には各ＬＥＤが有する順方向電圧降下Ｖ_ｆの温度依存性や駆動部２０を構成する各デバイスの特性バラツキ等を考慮して、３．９Ｖ以上の電圧を印加することが好ましい。 Therefore, in order to light each LED in the present embodiment, an applied voltage of 3.9 V or more obtained by adding the knee voltage 0.5 V to the forward voltage drop V _f = 3.4 V of the blue LED and the green LED is required. It is. In practice, it is preferable to apply a voltage of 3.9 V or higher in consideration of the temperature dependence of the forward voltage drop V _f of each LED and the variation in characteristics of each device constituting the drive unit 20.

一方で、青色ＬＥＤの順方向電圧降下Ｖ_ｆよりも小さい順方向電圧降下Ｖ_ｆを有する赤色ＬＥＤに、印加電圧Ｖ_ｏ＝３．９Ｖを印加すると電力損失が生じる。少なくとも青色ＬＥＤの順方向電圧降下Ｖ_ｆと赤色ＬＥＤの順方向電圧降下Ｖ_ｆとの電位差分が電力損失となる。本実施の形態においては、その電位差１．０Ｖが無駄な消費電力となる。 On the other hand, the red LED having a small forward voltage drop _{V f} than the forward voltage drop _{V f} of the blue LED, the application of a voltage applied _V o = 3.9V power loss. At least the potential difference between the forward voltage drop _Vf of the blue LED and the forward voltage drop _Vf of the red LED is a power loss. In the present embodiment, the potential difference of 1.0 V is wasteful power consumption.

そこで、本実施の形態では、各赤色ＬＥＤのカソード側から電源回路５０によって逆方向電圧Ｖ_ｒを印加し、カソード側の基準電位を上昇させる。上述したように、本実施の形態において、電源回路５０は、赤色ＬＥＤ１１１Ｒのカソードと赤色ＬＥＤ１２１Ｒのカソード、赤色ＬＥＤ１１２Ｒのカソード、赤色ＬＥＤ１２２Ｒのカソードに共通に並列接続しており、それら各赤色ＬＥＤに逆方向電圧Ｖ_ｒを印加する。 Therefore, in the present embodiment, the reverse voltage _Vr is applied from the cathode side of each red LED by the power supply circuit 50 to raise the reference potential on the cathode side. As described above, in the present embodiment, the power supply circuit 50 is commonly connected in parallel to the cathode of the red LED 111R, the cathode of the red LED 121R, the cathode of the red LED 112R, and the cathode of the red LED 122R. A directional voltage _Vr is applied.

本実施の形態のように、昇圧手段に電源回路５０を用いた場合、カソード側の電位を安定して昇圧することができる。また、その電源回路５０は電源供給回路３０より電源供給を受けて駆動するため、駆動部２０を構成する部品を少なくしながら電源回路５０を駆動部２０へ実装することができる。一方で、本実施の形態で示す電源回路５０は本発明の昇圧手段の一例であり、カソード側の電位を昇圧することができる手段であればその他の昇圧手段であっても良い。 When the power supply circuit 50 is used as the boosting means as in the present embodiment, the cathode side potential can be stably boosted. Further, since the power supply circuit 50 is driven by receiving power supply from the power supply circuit 30, the power supply circuit 50 can be mounted on the drive unit 20 while reducing the number of components constituting the drive unit 20. On the other hand, the power supply circuit 50 shown in the present embodiment is an example of a boosting unit of the present invention, and may be another boosting unit as long as it can boost the cathode side potential.

電源回路５０が印加する逆方向電圧Ｖ_ｒの大きさは、青色ＬＥＤの順方向電圧降下Ｖ_ｆと赤色ＬＥＤの順方向電圧降下Ｖ_ｆとの電位差以下であることが好ましい。逆方向電圧Ｖ_ｒがその電位差以下であれば、３色の各ＬＥＤの動作電圧が、各順方向電圧降下を下回ることがないため安定的な点灯制御が可能となる。また、逆方向電圧Ｖ_ｒが青色ＬＥＤの順方向電圧降下Ｖ_ｆと赤色ＬＥＤの順方向電圧降下Ｖ_ｆとの電位差と等しいとき、各ＬＥＤのアノードとカソード間に印加される実効的な動作電圧が各ＬＥＤで共通となり、損失となる消費電力量を安定的に統一させることができる。 The magnitude of the reverse voltage V _r to the power supply circuit 50 is applied is preferably less potential difference between the forward voltage drop V _f and red LED forward voltage drop V _f of the blue LED. If the reverse voltage _Vr is equal to or less than the potential difference, the operating voltage of each LED of the three colors does not fall below each forward voltage drop, so that stable lighting control is possible. The inverse time direction voltage V _r is equal to the potential difference between the forward voltage drop V _f and red LED forward voltage drop V _f of the blue LED, the effective operating voltage applied between the anode and cathode of each LED Is common to each LED, and the amount of power consumption that causes a loss can be stably unified.

本実施の形態では、青色ＬＥＤの順方向電圧降下Ｖ_ｆと赤色ＬＥＤの順方向電圧降下Ｖ_ｆとの電位差である１．０Ｖを逆方向電圧Ｖ_ｒとして印加する。これにより、各赤色ＬＥＤのカソード側の基準電位はＧＮＤ電位よりもＶ_ｒ＝１．０Ｖだけ高くなる。すなわち、各赤色ＬＥＤのアノードとカソード間の電位差は（Ｖ_ｏ−Ｖ_ｒ）となり、各赤色ＬＥＤの動作電圧は１．０Ｖだけ下がる。上述した無駄な電力消費を抑制することができる。 In the present embodiment, 1.0 V which is a potential difference between the forward voltage drop V _f of the blue LED and the forward voltage drop V _f of the red LED is applied as the reverse voltage V _r . Thereby, the reference potential on the cathode side of each red LED is higher than the GND potential by V _r = 1.0V. That is, the potential difference between the anode and the cathode of each red LED is (V _o −V _r ), and the operating voltage of each red LED is lowered by 1.0V. The useless power consumption described above can be suppressed.

（表示装置の点灯動作）
図４は、スイッチ４１とスイッチ４２、各ＯＮ／ＯＦＦ回路７０との入切と、各ＬＥＤの点灯制御のタイミングとを示す図であり、横軸は時間を表す。 (Lighting operation of display device)
FIG. 4 is a diagram showing on / off of the switch 41, the switch 42, and each ON / OFF circuit 70, and the timing of lighting control of each LED, and the horizontal axis represents time.

まず、図４に示したタイミングＴ１における表示装置１の点灯動作を説明する。スイッチ４１をＯＮ、スイッチ４２をＯＦＦにして、ＬＥＤアレイ２１１とＬＥＤアレイ２１２とに、電源供給回路３０から順方向の印加電圧Ｖ_ｏを供給する。その状態で、１列目の各赤色ＬＥＤに接続されたＯＮ／ＯＦＦ回路７１ＲをＰＷＭ制御すると、そのＯＮ／ＯＦＦ回路７１Ｒが導通したタイミングにおいて、ＬＥＤアレイ２１１に備わる赤色ＬＥＤ１１１Ｒが点灯する。この際、赤色ＬＥＤ１１１Ｒのカソード側の基準電位は、電源回路５０によって供給される逆方向の電圧によってＧＮＤ電位よりもＶ_ｒだけ高くなっている。同様に２列目の各赤色ＬＥＤに接続されたＯＮ／ＯＦＦ回路７２ＲをＰＷＭ制御して、ＬＥＤアレイ２１２に備わる赤色ＬＥＤ１１２Ｒを点灯制御する。赤色ＬＥＤ１１２Ｒのカソード側基準電位も、電源回路５０によってＧＮＤ電位よりＶ_ｒだけ高い電位に昇圧されている。また同じタイミングＴ１において、１列目の各緑色ＬＥＤに接続されたＯＮ／ＯＦＦ回路７１Ｇおよび１列目の各青色ＬＥＤに接続されたＯＮ／ＯＦＦ回路７１Ｂ、２列目の各緑色ＬＥＤに接続されたＯＮ／ＯＦＦ回路７２Ｇ、２列目の各青色ＬＥＤに接続されたＯＮ／ＯＦＦ回路７２Ｂに対してもＰＷＭ制御を行い、それぞれのＯＮ／ＯＦＦ回路に接続した緑色ＬＥＤ１１１Ｇおよび青色ＬＥＤ１１１Ｂ、緑色ＬＥＤ１１２Ｇ、青色ＬＥＤ１１２Ｂとを点灯制御する。この際、各緑色ＬＥＤ及び青色ＬＥＤのカソード側基準電位はＧＮＤ電位である。以上、タイミングＴ１において、１行目に配列されたＬＥＤアレイの点灯制御が完了する。なお、定電流回路６０は、各ＬＥＤに流れる電流を一定に制御するよう機能する。 First, the lighting operation of the display device 1 at the timing T1 shown in FIG. 4 will be described. ON the switch 41, the switch 42 is OFF, the on the LED array 211 and LED array 212, and supplies the forward direction of the applied voltage _{V o} from the power supply circuit 30. In this state, when the PWM control is performed on the ON / OFF circuit 71R connected to each red LED in the first column, the red LED 111R included in the LED array 211 is turned on when the ON / OFF circuit 71R is turned on. In this case, the reference potential of the cathode side of the red LED111R is higher by _{V r} than GND potential by reverse voltage supplied by the power supply circuit 50. Similarly, the ON / OFF circuit 72R connected to each red LED in the second column is PWM-controlled, and the red LED 112R included in the LED array 212 is controlled to be lit. Cathode side reference potential of the red LED112R also been boosted to as high potential _{V r} from the GND potential by a power supply circuit 50. At the same timing T1, the ON / OFF circuit 71G connected to each green LED in the first row and the ON / OFF circuit 71B connected to each blue LED in the first row are connected to each green LED in the second row. The ON / OFF circuit 72G and the ON / OFF circuit 72B connected to each blue LED in the second row are also subjected to PWM control, and the green LED 111G, the blue LED 111B, the green LED 112G connected to each ON / OFF circuit, Lighting control of the blue LED 112B is performed. At this time, the cathode-side reference potential of each green LED and blue LED is the GND potential. As described above, the lighting control of the LED array arranged in the first row is completed at the timing T1. The constant current circuit 60 functions to control the current flowing through each LED to be constant.

つづいて、図４に示したタイミングＴ２における表示装置１の点灯動作を説明する。スイッチ４１をＯＦＦ、スイッチ４２をＯＮにして、ＬＥＤアレイ２２１とＬＥＤアレイ２２２とに電源供給回路３０から順方向の印加電圧Ｖ_ｏを供給する。その状態で、１列目の各赤色ＬＥＤに接続されたＯＮ／ＯＦＦ回路７１ＲをＰＷＭ制御し、そのＯＮ／ＯＦＦ回路７１Ｒが導通したタイミングにおいて、ＬＥＤアレイ２２１に備わる赤色ＬＥＤ１２１Ｒが点灯する。この際、赤色ＬＥＤ１２１Ｒのカソード側の基準電位は、電源回路５０によって供給される逆方向の電圧によってＧＮＤ電位よりもＶ_ｒだけ高くなっている。同様に２列目の各赤色ＬＥＤに接続されたＯＮ／ＯＦＦ回路７２ＲをＰＷＭ制御して、ＬＥＤアレイ２２２に備わる赤色ＬＥＤ１２２Ｒを点灯制御する。赤色ＬＥＤ１２２Ｒのカソード側基準電位も、電源回路５０によってＧＮＤ電位よりＶ_ｒだけ高い電位に昇圧されている。また同じタイミングＴ２において、１列目の各緑色ＬＥＤに接続されたＯＮ／ＯＦＦ回路７１Ｇおよび１列目の各青色ＬＥＤに接続されたＯＮ／ＯＦＦ回路７１Ｂ、２列目の各緑色ＬＥＤに接続されたＯＮ／ＯＦＦ回路７２Ｇ、２列目の各青色ＬＥＤに接続されたＯＮ／ＯＦＦ回路７２Ｂとに対してもＰＷＭ制御を行い、それぞれのＯＮ／ＯＦＦ回路に接続した緑色ＬＥＤ１２１Ｇおよび青色ＬＥＤ１２１Ｂ、緑色ＬＥＤ１２２Ｇ、青色ＬＥＤ１２２Ｂとを点灯制御する。それら各緑色ＬＥＤ及び青色ＬＥＤのカソード側基準電位はＧＮＤ電位である。以上にて、タイミングＴ２において、２行目に配列されたＬＥＤアレイの点灯制御が完了する。 Next, the lighting operation of the display device 1 at the timing T2 shown in FIG. 4 will be described. OFF switch 41, the switch 42 is ON, the supplies forward direction of the applied voltage _{V o} to the LED array 221 and LED array 222 from the power supply circuit 30. In this state, PWM control is performed on the ON / OFF circuit 71R connected to each red LED in the first column, and the red LED 121R included in the LED array 221 is turned on when the ON / OFF circuit 71R is turned on. At this time, the reference potential on the cathode side of the red LED 121 </ b> _{R is} higher than the GND potential by Vr due to the reverse voltage supplied by the power supply circuit 50. Similarly, the ON / OFF circuit 72R connected to each red LED in the second column is PWM-controlled, and the red LED 122R included in the LED array 222 is controlled to be lit. Cathode side reference potential of the red LED122R also been boosted to as high potential _{V r} from the GND potential by a power supply circuit 50. At the same timing T2, the ON / OFF circuit 71G connected to each green LED in the first row and the ON / OFF circuit 71B connected to each blue LED in the first row are connected to each green LED in the second row. PWM control is also performed on the ON / OFF circuit 72G and the ON / OFF circuit 72B connected to each blue LED in the second row, and the green LED 121G, the blue LED 121B, and the green LED 122G connected to each ON / OFF circuit. The blue LED 122B is turned on. The cathode side reference potential of each green LED and blue LED is the GND potential. Thus, the lighting control of the LED array arranged in the second row is completed at the timing T2.

以降、タイミングＴ１とタイミングＴ２の点灯制御を繰り返す。すなわち、スイッチ４１とスイッチ４２により、ＬＥＤアレイの１行目の点灯制御と２行目の点灯制御を交互に繰り返し、また各ＬＥＤの種類ごとに各列に設けられたＯＮ／ＯＦＦ回路７０によって点灯時の輝度をＰＷＭ制御し、文字・図形・画像情報等の映像表示を行う。 Thereafter, the lighting control at timing T1 and timing T2 is repeated. That is, the lighting control of the first row and the lighting control of the second row of the LED array are alternately repeated by the switch 41 and the switch 42, and the lighting is performed by the ON / OFF circuit 70 provided in each column for each LED type. The brightness of the hour is PWM controlled to display images such as text, graphics, and image information.

なお、図２の表示装置１が備える表示部１０は、２行×２列の計４個のＬＥＤアレイを備えるが任意の行数と列数の組み合わせで構成してもよい。また、本実施の形態の表示装置１は、スイッチ４１とスイッチ４２とを用いて２ラインスキャンの点灯制御を実施しているが、必ずしも２ライン単位で行う必要はない。表示部１０を構成するＬＥＤアレイの数に応じて設定すればよく、例えば３２ライン単位で時分割処理してもよい。 The display unit 10 included in the display device 1 of FIG. 2 includes a total of four LED arrays of 2 rows × 2 columns, but may be configured by any combination of the number of rows and the number of columns. Further, the display device 1 according to the present embodiment performs the lighting control of the two-line scan using the switch 41 and the switch 42, but it is not necessarily performed in units of two lines. What is necessary is just to set according to the number of LED arrays which comprise the display part 10, for example, you may carry out a time division process per 32 lines.

（効果）
従来のアノードコモン接続の表示装置、すなわち昇圧手段を備えない表示装置の消費電力と、本実施の形態に示した昇圧手段を備える表示装置１の消費電力とを比較する。両装置の消費電力の差は、印加電圧の差分×電流×ＯＮ/ＯＦＦ比で計算できる。仮に、ＯＮ/ＯＦＦ比を０．２５とすると、印加電圧の差分は１．０Ｖ、電流は１０ｍＡであるから、１個の赤色ＬＥＤあたり２．５ｍＷの消費電力の低減できることになる。例えば、表示装置１がフルハイビジョンの表示装置である場合、そのＬＥＤアレイの数つまり画素数は２００万個以上であるため、消費電力の削減効果は５ｋＷ以上となる。 (effect)
The power consumption of the conventional anode common connection display device, that is, the display device not provided with the boosting means, is compared with the power consumption of the display device 1 provided with the boosting means shown in the present embodiment. The difference in power consumption between the two devices can be calculated by applying voltage difference × current × ON / OFF ratio. If the ON / OFF ratio is 0.25, the applied voltage difference is 1.0 V and the current is 10 mA. Therefore, power consumption of 2.5 mW per red LED can be reduced. For example, when the display device 1 is a full high-definition display device, the number of LED arrays, that is, the number of pixels is 2 million or more, so the power consumption reduction effect is 5 kW or more.

以上のように、本実施の形態の表示装置１は、半導体発光デバイスアレイ２００を含む表示部１０と、表示部１０を電気的に駆動する駆動部２０とを備える表示装置１であって、半導体発光デバイスアレイ２００は、同じ半導体発光デバイスアレイ２００に含まれる他の半導体発光デバイス１００が有する順方向電圧降下Ｖ_ｆとは異なる順方向電圧降下Ｖ_ｆを有する少なくとも１つの半導体発光デバイス１００を含み、駆動部２０は各半導体発光デバイスアレイ２００に含まれる半導体発光デバイス１００の各アノードに共通の順方向の印加電圧Ｖ_ｏを供給する電源供給回路３０と、各半導体発光デバイスアレイ２００に含まれる半導体発光デバイス１００のうち、最大の順方向電圧降下Ｖ_ｆを有する半導体発光デバイス１００とは異なる少なくとも１つの半導体発光デバイス１００のカソード側に接続し、当該カソード側の電位を昇圧させる少なくとも１つの電源回路５０を昇圧手段として備える。 As described above, the display device 1 according to the present embodiment is a display device 1 that includes the display unit 10 including the semiconductor light emitting device array 200 and the drive unit 20 that electrically drives the display unit 10. The light emitting device array 200 includes at least one semiconductor light emitting device 100 having a forward voltage drop V _f different from the forward voltage drop V _f of other semiconductor light emitting devices 100 included in the same semiconductor light emitting device array 200, driver 20 semiconductor emission and power supply circuit 30 for supplying an applied voltage V _o of the common forward to each anode of the semiconductor light emitting device 100 included in the semiconductor light-emitting device array 200, included in the semiconductor light-emitting device array 200 Of the devices 100, different from the semiconductor light emitting device 100 having the largest forward voltage drop V _f. At least one power supply circuit 50 that is connected to the cathode side of at least one semiconductor light emitting device 100 and boosts the potential on the cathode side is provided as a boosting unit.

このような構成により、表示装置１は各半導体発光デバイス１００のアノード−カソード間へ適正な動作電圧を供給できる。すなわち、本発明に係る表示装置１は、アノードコモン接続を有する従来の表示装置において、他の半導体発光デバイス１００よりも小さな順方向電圧降下Ｖ_ｆを有する半導体発光デバイス１００で発生していた無駄な電力消費を低減することができる。その結果、駆動部２０の発熱も抑制でき、各半導体発光デバイス１００の長寿命化が可能となるなど表示装置１の信頼性が向上する。また、多くのメーカが製品化しているアノードコモン型の半導体発光デバイスドライバを使用することができるので入手性がよく表示装置１の低コスト化が可能である。 With such a configuration, the display device 1 can supply an appropriate operating voltage between the anode and the cathode of each semiconductor light emitting device 100. That is, the display device 1 according to the present invention is a wasteful generation that has occurred in the semiconductor light emitting device 100 having a smaller forward voltage drop V _f than the other semiconductor light emitting devices 100 in the conventional display device having the anode common connection. Power consumption can be reduced. As a result, the heat generation of the drive unit 20 can also be suppressed, and the reliability of the display device 1 is improved, such as the lifetime of each semiconductor light emitting device 100 being increased. In addition, since an anode common type semiconductor light emitting device driver commercialized by many manufacturers can be used, the availability is high and the cost of the display device 1 can be reduced.

また、本発明に係る表示装置１が備える昇圧手段が昇圧する電圧の大きさＶ_ｒは、半導体発光デバイスアレイ２００に含まれる半導体発光デバイス１００が有する最大の順方向電圧降下Ｖ_ｆと、昇圧手段が接続された半導体発光デバイス１００が有する順方向電圧降下Ｖ_ｆとの差分以下であることが好ましい。これにより、昇圧手段が接続された各半導体発光デバイス１００の動作電圧が、すなわちアノード−カソード間に印加される電圧が、それら半導体発光デバイス１００の順方向電圧降下Ｖ_ｆを下回ることがないため安定的な点灯制御が可能となる。 In addition, the magnitude V _r of the voltage boosted by the boosting unit included in the display device 1 according to the present invention is the maximum forward voltage drop V _{f of the} semiconductor light emitting device 100 included in the semiconductor light emitting device array 200 and the boosting unit. Is preferably equal to or less than the difference from the forward voltage drop V _{f of} the semiconductor light emitting device 100 to which is connected. As a result, the operating voltage of each semiconductor light emitting device 100 to which the boosting means is connected, that is, the voltage applied between the anode and the cathode does not fall below the forward voltage drop V _f of these semiconductor light emitting devices 100, so that it is stable. Lighting control is possible.

また、本発明に係る表示装置１が備える昇圧手段は、最大の順方向電圧降下Ｖ_ｆを有する半導体発光デバイス１００とは異なる少なくとも１つの半導体発光デバイス１００のカソード側から逆方向電圧Ｖ_ｒを印加して、そのカソード側の電位を昇圧する電源回路５０であることが好ましい。これにより、そのカソード側の電位を安定して昇圧することができる。また、その電源回路５０は電源供給回路３０より電源供給を受けて駆動することが好ましい。これにより、駆動部２０を構成する部品を少なくしながら電源回路５０を駆動部２０へ実装することができる。 Further, the boosting means display device 1 according to the present invention comprises the application of a reverse voltage V _r from the cathode side of the at least one different semiconductor light emitting device 100 includes a semiconductor light emitting device 100 having the greatest forward voltage drop V _f Thus, the power supply circuit 50 that boosts the potential on the cathode side is preferable. As a result, the potential on the cathode side can be stably boosted. The power supply circuit 50 is preferably driven by receiving power supply from the power supply circuit 30. Thereby, the power supply circuit 50 can be mounted on the drive unit 20 while reducing the number of components constituting the drive unit 20.

また、本発明に係る表示装置１が備える各半導体発光デバイスアレイ２００は、発光波長が異なる複数の半導体発光デバイス１００を含むことが好ましい。発光波長は半導体発光デバイス１００のバンドギャップに概ね一致しており、そのバンドギャップは活性層材料に依存する。よって発光波長は順方向電圧降下Ｖ_ｆと関連している。ゆえに、発光波長の長い半導体発光デバイスのカソード側の基準電圧を昇圧手段により昇圧することで、発光波長の長い半導体発光デバイスで発生していた無駄な電力消費を特に低減することができる。 In addition, each semiconductor light emitting device array 200 included in the display device 1 according to the present invention preferably includes a plurality of semiconductor light emitting devices 100 having different emission wavelengths. The emission wavelength substantially matches the band gap of the semiconductor light emitting device 100, and the band gap depends on the active layer material. Thus, the emission wavelength is related to the forward voltage drop _Vf . Therefore, by boosting the reference voltage on the cathode side of the semiconductor light emitting device having a long emission wavelength by the boosting means, it is possible to particularly reduce the wasteful power consumption generated in the semiconductor light emitting device having a long emission wavelength.

また、本発明に係る表示装置１が備える各半導体発光デバイスアレイ２００は、発光波長が赤色帯域のＬＥＤと、発光波長が緑色帯域のＬＥＤと、発光波長が青色帯域のＬＥＤとを含むことが好ましい。表１に示したように、各色ＬＥＤの順方向電圧降下Ｖ_ｆは活性層材料と関係がある。よって、上記のような各色ＬＥＤ１００を含むＬＥＤアレイ２００を備える表示装置１において、青色ＬＥＤ１００Ｂや緑色ＬＥＤ１００Ｇよりも小さな順方向電圧降下Ｖ_ｆを有する赤色ＬＥＤ１００Ｒで発生していた無駄な電力消費を特に低減することができる。 In addition, each semiconductor light emitting device array 200 included in the display device 1 according to the present invention preferably includes an LED having a red light emission wavelength, an LED having a green light emission wavelength, and an LED having a blue light emission wavelength. . As shown in Table 1, the forward voltage drop V _f of each color LED is related to the active layer material. Therefore, in the display device 1 including the LED array 200 including each color LED100 as described above, particularly wasteful power consumption which occurs in the red LED100R with blue LED100B or green LED100G small forward voltage drop _{V f} than reduction can do.

また、本発明に係る表示装置１が備える表示部１０は、各半導体発光デバイスアレイ２００に含まれる各半導体発光デバイス１００の各アノードがアノードコモンに接続したアノードコモン端子をさらに備え、電源供給回路３０はそのアノードコモン端子に接続し、各アノードに対し共通の順方向の電圧Ｖ_ｏを印加する。これにより、電源供給回路３０から各半導体発光デバイス１００へ共通の印加電圧Ｖ_ｏを供給するこができる。また、電源供給回路３０から各半導体発光デバイス１００までの回路を簡略化できる。すなわち電源供給回路３０に、多くのメーカが製品化しているアノードコモン型の半導体発光デバイスドライバを使用することができるので入手性がよく表示装置１の低コスト化が可能となる。 The display unit 10 included in the display device 1 according to the present invention further includes an anode common terminal in which each anode of each semiconductor light emitting device 100 included in each semiconductor light emitting device array 200 is connected to an anode common, and the power supply circuit 30. It is connected to the anode common terminal, for applying a voltage V _o of the common forward to each anode. Thus, it is this which supplies a common voltage applied V _o from the power supply circuit 30 to the semiconductor light-emitting device 100. Further, the circuit from the power supply circuit 30 to each semiconductor light emitting device 100 can be simplified. That is, since the anode common type semiconductor light emitting device driver commercialized by many manufacturers can be used for the power supply circuit 30, the availability is good and the cost of the display device 1 can be reduced.

また、本発明に係る表示装置１が備える各半導体発光デバイスアレイ２００は、表示部１０の面内で第１の方向と第２の方向とに配列され、駆動部２０は、その第１の方向に配列された各半導体発光デバイスアレイ２００の各アノードコモン端子に共通して接続される配線上に設けられ、第１の方向に配列された各半導体発光デバイスアレイ２００に流れる電流または印加する電圧の入出力を時分割制御する第１の点灯制御手段と、第２の方向に配列された各半導体発光デバイスアレイ２００に含まれる各半導体発光デバイス１００の各カソードに接続する配線上に設けられ、第２の方向に配列された各半導体発光デバイスアレイ２００に含まれる各半導体発光デバイスに流れる電流または印加する電圧の入出力を時分割制御する第２の点灯制御手段とをさらに備える。このような構成により、第１の点灯制御手段は半導体発光デバイスアレイの１行目の点灯制御と２行目の点灯制御を交互に繰り返し、また第２の点灯制御手段は各半導体発光デバイスの点灯時の輝度をＰＷＭ制御を行う。これにより、表示装置１はラインスキャンにより文字・図形・画像情報等の映像表示が可能となる。 Moreover, each semiconductor light-emitting device array 200 with which the display apparatus 1 which concerns on this invention is provided is arranged in the 1st direction and 2nd direction within the surface of the display part 10, and the drive part 20 is the 1st direction. Current flowing through each semiconductor light emitting device array 200 arranged in the first direction and applied to the common electrode connected to each anode common terminal of each semiconductor light emitting device array 200 arranged in the first direction. First lighting control means for time-division control of input / output, and wiring connected to each cathode of each semiconductor light emitting device 100 included in each semiconductor light emitting device array 200 arranged in the second direction, 2nd lighting which carries out time division control of the input / output of the electric current which flows into each semiconductor light-emitting device contained in each semiconductor light-emitting device array 200 arranged in 2 directions, or the voltage to apply Further comprising a control means. With such a configuration, the first lighting control means alternately repeats the lighting control for the first row and the lighting control for the second row of the semiconductor light emitting device array, and the second lighting control means turns on each semiconductor light emitting device. The brightness of the hour is PWM controlled. As a result, the display device 1 can display images of characters, graphics, image information, and the like by line scanning.

なお、本発明は、その発明の範囲内において、実施の形態を適宜、変形、省略することが可能である。 In the present invention, the embodiments can be appropriately modified and omitted within the scope of the invention.

＜実施の形態の変形例＞
上記実施の形態では、昇圧手段である電源回路５０が赤色ＬＥＤのカソード側にのみ接続する表示装置１を示したが、複数種類のＬＥＤに昇圧手段が接続する表示装置であっても良い。例えば、表示装置１が、順方向電圧降下Ｖ_ｆ＝２．４Ｖの赤色ＬＥＤと、順方向電圧降下Ｖ_ｆ＝３．４Ｖの緑色ＬＥＤと、順方向電圧降下Ｖ_ｆ＝２．９Ｖの青色ＬＥＤとを備える場合、表示装置１は、最大の順方向電圧降下Ｖ_ｆを有する緑色ＬＥＤとは異なるＬＥＤ、すなわち赤色ＬＥＤのカソード側と青色ＬＥＤのカソード側とのそれぞれに接続する昇圧手段を備えても良い。 <Modification of Embodiment>
In the above embodiment, the display device 1 in which the power supply circuit 50 as the boosting unit is connected only to the cathode side of the red LED is shown, but a display device in which the boosting unit is connected to a plurality of types of LEDs may be used. For example, the display device 1, the red LED in the forward voltage drop _V f = 2.4V, and a green LED in the forward voltage drop _V f = 3.4 V, the forward voltage drop _V f = 2.9 V blue LED of , The display device 1 includes boosting means connected to the LED different from the green LED having the maximum forward voltage drop V _f , that is, the cathode side of the red LED and the cathode side of the blue LED. Also good.

本変形例において、緑色ＬＥＤの順方向電圧降下Ｖ_ｆ＝３．４Ｖと赤色ＬＥＤの順方向電圧降下Ｖ_ｆ＝２．４Ｖと差は、上述した実施の形態と同じく１．０Ｖである。よって、各赤色ＬＥＤのカソード側に電源回路５０を接続し、電源回路５０から逆方向電圧Ｖ_ｒ＝１．０Ｖを供給する。それにより、各赤色ＬＥＤのカソード側の基準電位を１．０Ｖだけ昇圧させる。また、緑色ＬＥＤの順方向電圧降下Ｖ_ｆ＝３．４Ｖと青色ＬＥＤの順方向電圧降下Ｖ_ｆ＝２．９Ｖと差は０．５Ｖである。よって、各青色ＬＥＤのカソード側に電源回路５０を接続し、電源回路５０から逆方向電圧Ｖ_ｒ＝０．５Ｖを供給する。それにより、各青色ＬＥＤのカソード側の基準電位を０．５Ｖだけ昇圧する。なお、表示装置１は、青色ＬＥＤに逆方向電圧Ｖ_ｒ＝０．５Ｖを印加する電源回路５０と、赤色ＬＥＤに逆方向電圧Ｖ_ｒ＝１．０Ｖを印加する電源回路５０とを個別に備えても良いし、同じ電源回路５０を共用しても良い。 In this modification, the difference between the forward voltage drop V _f = 3.4 V of the green LED and the forward voltage drop V _f = 2.4 V of the red LED is 1.0 V as in the above-described embodiment. Therefore, the power supply circuit 50 is connected to the cathode side of each red LED, and the reverse voltage V _r = 1.0 V is supplied from the power supply circuit 50. Thereby, the reference potential on the cathode side of each red LED is boosted by 1.0V. Further, the difference between the forward voltage drop V _f = 3.4V of the green LED and the forward voltage drop V _f = 2.9V of the blue LED is 0.5V. Therefore, the power supply circuit 50 is connected to the cathode side of each blue LED, and the reverse voltage V _r = 0.5 V is supplied from the power supply circuit 50. Thereby, the reference potential on the cathode side of each blue LED is boosted by 0.5V. The display device 1 includes a power circuit 50 that applies a reverse voltage V _r = 0.5 V to the blue LED and a power circuit 50 that applies a reverse voltage V _r = 1.0 V to the red LED. Alternatively, the same power supply circuit 50 may be shared.

従来のアノードコモン接続の表示装置、すなわち昇圧手段を備えない表示装置の消費電力と、本実施の形態の変形例に示した昇圧手段を備える表示装置１との消費電力を比較する。上記の実施の形態と同様に、ＯＮ/ＯＦＦ比を０．２５とすると、１個の赤色ＬＥＤあたり２．５ｍＷの消費電力の低減が可能である。また、１個の青色ＬＥＤあたり１．２５ｍＷの消費電力の低減が可能である。すなわち本変形例においては、１組のＬＥＤアレイあたり３．７５ｍＷの消費電力の低減が可能である。表示装置１がフルハイビジョンの表示装置である場合、消費電力の削減効果は７．５ｋＷ以上となる。 The power consumption of a conventional anode common connection display device, that is, a display device that does not include the boosting means, and the power consumption of the display device 1 that includes the boosting means shown in the modification of the present embodiment will be compared. Similarly to the above embodiment, when the ON / OFF ratio is 0.25, the power consumption can be reduced by 2.5 mW per red LED. In addition, the power consumption can be reduced by 1.25 mW per blue LED. That is, in this modification, the power consumption can be reduced by 3.75 mW per set of LED arrays. When the display device 1 is a full high-definition display device, the power consumption reduction effect is 7.5 kW or more.

１表示装置、２入力端子、３映像信号処理部、４輝度補正部、１０表示部、２０駆動部、３０電源供給回路、４１スイッチ（第１の点灯制御手段）、４２スイッチ（第１の点灯制御手段）、５０電源回路（昇圧手段）、６０定電流回路、７０ＯＮ／ＯＦＦ回路（第２の点灯制御手段）、８０制御回路、１００半導体発光デバイスＬＥＤ、１００Ｂ青色ＬＥＤ、１００Ｇ緑色ＬＥＤ、１００Ｒ赤色ＬＥＤ、２００半導体発光デバイスアレイ、３００アノードコモン端子、Ｌ１ライン、Ｌ２ライン、Ｔ１タイミング、Ｔ２タイミング、Ｖ_ｆ順方向電圧降下、Ｖ_ｏ印加電圧、Ｖ_ｒ逆方向電圧。 DESCRIPTION OF SYMBOLS 1 Display apparatus, 2 input terminal, 3 Video signal processing part, 4 Brightness correction part, 10 Display part, 20 Drive part, 30 Power supply circuit, 41 Switch (1st lighting control means), 42 Switch (1st lighting) Control means), 50 power supply circuit (boost means), 60 constant current circuit, 70 ON / OFF circuit (second lighting control means), 80 control circuit, 100 semiconductor light emitting device LED, 100B blue LED, 100G green LED, 100R red LED, 200 semiconductor light emitting device array, 300 anode common terminal, L1 line, L2 line, T1 timing, T2 timing, _{V f} forward voltage drop, _{V o} applied voltage, _{V r} reverse voltage.

Claims

A display device comprising: a display unit including a semiconductor light emitting device array; and a drive unit that electrically drives the display unit,
The semiconductor light emitting device array is:
Including at least one semiconductor light emitting device having a forward voltage drop different from a forward voltage drop of other semiconductor light emitting devices included in the same semiconductor light emitting device array;
The driving means includes
A power supply for applying a common forward voltage to each anode of the semiconductor light emitting devices included in each of the semiconductor light emitting device arrays;
Of the semiconductor light emitting devices included in each of the semiconductor light emitting device arrays, connected to the cathode side of at least one semiconductor light emitting device different from the semiconductor light emitting device having the maximum forward voltage drop, and the potential on the cathode side And at least one boosting means for boosting the pressure.

2. The magnitude of the voltage boosted by the booster is equal to or less than a difference between the maximum forward voltage drop and a forward voltage drop of the semiconductor light emitting device to which the booster is connected. Display device.

The display device according to claim 1, wherein the boosting unit is a power supply circuit that boosts the potential on the cathode side by applying a reverse voltage from the cathode side.

4. The display device according to claim 1, wherein each of the semiconductor light emitting device arrays includes a plurality of semiconductor light emitting devices having different emission wavelengths.

5. The semiconductor light emitting device array according to claim 1, wherein each of the semiconductor light emitting device arrays includes an LED having an emission wavelength in a red band, an LED having an emission wavelength in a green band, and an LED having an emission wavelength in a blue band. Display device.

The display unit
An anode common terminal in which each anode of each of the semiconductor light emitting devices included in each semiconductor light emitting device array is connected to an anode common;
The display device according to claim 1, wherein the power source is connected to the anode common terminal and applies a common forward voltage to the anodes.

The semiconductor light emitting device array is:
Are arranged in a first direction and a second direction in the plane of the display unit,
The driving means includes
Each semiconductor light emitting device array arranged in the first direction is provided on a wiring commonly connected to each anode common terminal of each of the semiconductor light emitting device arrays arranged in the first direction. First lighting control means for performing time-sharing control of input / output of flowing current or applied voltage;
Each of the semiconductor light emitting devices arranged on the wiring connected to each of the cathodes of each of the semiconductor light emitting devices included in each of the semiconductor light emitting device arrays arranged in the second direction and arranged in the second direction The display device according to claim 6, further comprising: a second lighting control unit that performs time-sharing control of input / output of a current flowing through each semiconductor light-emitting device included in the array or an applied voltage.